1. Field of the Invention
The present invention relates to aircraft gas turbine engine starters and generators.
2. Description of Related Art
Aircraft gas turbine engines typically include a fan section followed by a core engine having, in serial flow arrangement, a compressor which compresses airflow entering the engine, a combustor which burns a mixture of fuel and air, and a high-pressure turbine section followed by a low pressure turbine section which extracts energy from airflow discharged from the core engine to power the fan section which generates thrust.
Aircraft and aircraft engine accessories are mechanically driven by the engine through a power take-off shaft connected to an engine accessory gearbox. Among the accessories mounted to the gearbox is a starter motor for starting the gas turbine engine and a generator to generate electrical power for the aircraft. It is known to provide a single starter/generator to provide both starting and electrical power generation. Starter/generators with and without brushes, referred to as brushed and brushless, are well known for electrical generation and starting in aircraft gas turbine engines. It is known to use air and/or oil coolers for cooling the starter/generators. The electrical generation in such units is limited in amperage and often require complicated cooling apparatus including cooling fans and ducts which leads to power and fuel robbing parasitic flows required for air cooled starter/generators using brushes.
It is highly desirable to reduce the weight of aircraft gas turbine engine starter/generators while increasing the amount of amperage output. It is highly desirable to reduce the amount and complexity of cooling apparatus for the starter/generators. It is highly desirable to reduce power and fuel robbing parasitic flows required for air cooled starter/generators using brushes.